P1294: REAL-WORLD OUTCOMES OF 2149 NEWLY DIAGNOSED TRANSPLANT-ELIGIBLE MULTIPLE MYELOMA PATIENTS
Authors: Tereza Popková, Ludek Pour, Ivan Spicka, Jakub Radocha, Alexandra Jungova, Jiri Minarik, Petr Pavlíček, Tomas Jelínek, Marta Krejčí, Jan Straub, Vladimir Maisnar, Tereza Dekojová, Tomáš Pika, Jan Soukup, Lenka Pospíšilová, Roman Hájek
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: Even though exceedingly effective agents and novel therapeutic strategies are being developed, high-dose chemotherapy followed by autologous stem cell transplantation (HDT/ASCT) has repeatedly proved its importance for fit, newly diagnosed multiple myeloma (NDMM) patients (pts) in prospective clinical trials. Aims: The aim of this study is to provide a comprehensive understanding of HDT/ASCT effectiveness and safety in the real-world heterogenous population of NDMM pts. Methods: We conducted a retrospective, observational study of the Czech Myeloma Group Registry of Monoclonal Gammopathies (RMG). It is a clinical registry established in 2006 that has gathered detailed real-world data in more than 13000 patients who have all signed an informed consent. Only Czech pts who received HDT/ASCT as a part of their initial MM therapy were included. Results: By August 2021, a total of 2149 pts were identified. At the time of MM diagnosis, the median age of the cohort was 59 (42-68) years with 11% (247/2149) of pts over 65 years of age; 45%/31%/24% of pts were ISS stage I/II/III; high-risk cytogenetic features [t(4;14), t(14;16), del(17p)] were found in 33% (243/746) of cases. The combinations of agents used in the induction regimen were proteasome inhibitor (PI), immunomodulatory drug (IMiD) and glucocorticoid (GC) in 29% (631/2149); PI, GC and chemotherapy (CHT) in 24% (525/2149); GC and CHT in 23% (486/2149); IMiD, GC and CHT in 16% (336/2149) and other in 9% (171/2149) of pts. Tandem HDT/ASCT was performed in 12% (268/2149) of cases. Nine percent (198/2149) of pts were treated within a clinical study. After a median follow up of 56 months, mOS and mPFS was 97 (92.8-105.0) and 36 (34.0-37.7) months, respectively. There was a clear improvement in the depth of response (CR+sCR 32% vs. 13%) after HDT/ASCT compared to the post-induction period. Transplant-related mortality (TRM) was equal to 0.7% (16/2141). Age was shown to be a prognostic marker for overall survival – mOS for <50, 51-60, 61-70 and >71year-olds was 135, 101, 88 and 43 months, respectively (p<0.001). The use of HDT/ASCT did not overcome the adverse prognosis of patients with high-risk cytogenetic features – mOS was 101 vs. 61 months (p<0.001) and mPFS was 37 and 25 months (p<0.001) for patients with standard and high cytogenetic risk, respectively. Patients harboring the amplification 1q21 had significantly worse outcome - mOS was 67 vs. 101 months (p<0.001). Whereas translocation (11;14) did not show any influence on survival – mOS 96 vs. 96 months (p=0.784). Patients responding with at least CR after HDT/ASCT achieved significantly better overall survival – mOS was 132, 88 and 90 months for CR+sCR, VGPR, PR and worse, respectively (p<0.001). Our data showed a clinically relevant improvement in PFS when tandem HDT/ASCT was used for patients with high-risk cytogenetics compared to single HDT/ASCT– mPFS 31 vs. 25 months (p=0.132). Summary/Conclusion: RMG is committed to provide robust high-quality real-world data. HDT/ASCT has been a well-established, efficient, and safe procedure and remains a standard of care for first-line treatment. Our analysis of 2149 newly diagnosed transplant-eligible pts confirms high effectiveness (mPFS 36 months) and out-standing safety (TRM 0,7%) of the procedure with long-term survival (mOS 97 months) for eligible NDMM pts. Nevertheless, the concept of tailoring therapy and cellular immunotherapies will undoubtedly bring changes potentially even a revolution in the near future. Keywords: Autologous hematopoietic stem cell transplantation, High risk, Multiple myeloma